Electric switchgear



Feb. 2, 1932. A 1. CHRISTIE ELECTRIC SWITCH GEAR 2 sheets-sheet Filed Feb. 2l, 1931 Feb. 2, 1932. J. CHRISTIEu ELECTRIC SWITCH GEAR Filed Feb. 21, 1931 2 Sheets-Sheet 2 Patented Feb. 2, 1932 UNITED STATES PATENT OFFICE JOHN CHRISTIE, F SUNDERLAND, ENGLAND, ASSIGNOR T0 A. REYROLLE & COMPANY LIMITED, 0F HEBBURN-ON-TYNE, ENGLAND, A COMPANY 0F GREAT BRITAIN ELECTRIC SWITCHGEAR Application led February 21, 1931,. Serial No.

" mission through a common circuit-breaker.

In switchgear of this general type the busbars are sometimes in separate chambers and are kconnected through isolating or selecting switches to a common connection in an inter mediate chamber', such common connection leading to the main circuit-breaker.

In duplicate busbar'systems particularly with extrahigh voltage, it is desirable that if one vbar be out of service it shall be isolated 'asfeiliciently as possible from the other bar and from the circuit-breaker, and it is therefore inadvisable to employ the common connection above referred to. Further, the vuse of such a common connection where the two busbars carry different voltages is inadmissible.

In switchgear according to the present invention each busbar is in a separate chamber and its connection to the main circuit-breaker is effected by a rotary member or isolating switch which makes and breaks the circuit'at two points.

Preferably the separate chambers each containing one of the busbars are arranged over another chamber, and passing vthrough each busbar chamber into the chamber beneath it is a rotary member in the form of an insulating bushing surrounding a conductor having at each end a switch arm. The arm at the upper end makes connection with the busbar andthat at the lower end with a condu'ctorfleading down 'to 'the main circuitbreaker. Thus, i the arrangement comprises for each of the busbars vwhat may be termed a double-ended rotary isolating switch which iscapable of connecting its own busbar with thecircuit-breaker or` 'of breaking such connection at ltwo points', one in the separate busbar chamber and the other in the intermediate vchamber. It will be appreciated therefore that the` isolation of either busbar can be most completelyand readilyveifected. A convenient practical construction according to the invention isIillust-rated by way of 517,610, and in Great Britain March 26, 19730.

example in the accompanying drawings, in

which Figure 1 is a front elevation parts being shown in section,

Figure 2 is a section on the line 2 2 of Figure l, and t Figure 3 is a'horizontal section taken just beneath the cover plate of the uppermost chamber,

In this arrangement the two busbars A are led into separate oil-filled chambers B, which are disposed side-by-side above a third oililled chamber C. Passing through from each busbar chamber B into the lower chamber C is a conductor D mounted within an insulating bushing D1. Each conductor D carries two switch arms E F respectively at its upper and lower ends. The whole bushing D1 with the conductor D and switch arms E F is rotatable by means of the mechanism indi- 2' ductor and bushing in theV earthed position.

In theoperative position the upper switch arm E engages with a. cont-act A2 to which the busbar is connected, and the lower switch arm F' engages with a contact ring H1 surrounding a tubular casing H in the chamber C. In the earthed position the two switch arms E F engage respectively with earthed contacts El F1 mounted on the walls of the chambers.

The tubular casing I-I extends from the top to the bottom of the chamber C and a detachable cover plate H2 is provided over its upper end. Atits lower end the casing I-I is provided with a ieXible4 extension H2, which is bolted on to the cover plate J2 of the circuit-breaker tank J. The casing H contains a conductor K surrounded by a condenser-insulator K1. At its upper end the conductor K carries a spring Contact K2 engaging with the inside of the contact ring H1, whilst at the lower end the conductor makes a plug and socket connection with ,one oi? the iiXed circuit-breaker contacts L. The other fixed circuit-breaker contact L1, which is connected to the Contact L through a movable bridging contact L2 in the usual manner, is connected through a plug and socket ConnerL tion to a conductor M surrounded by a condenser-insulator M1. The conductor M is mounted within a tubular casing N which passes through an oil-illed chamber O, its upper end being closed by a cover plate N2, and is provided at its lower end with a flexible extension N3. The conductor M carries at its upper end a spring contact M2 engaging with the inside of a contact ring N1 on the tubular casing N. The arrangement ot the conductor M and tubular casing N is simV ilar to that of the conductor K and casing PI, and is such that on opening up the cover plates H2 N2 and unbolting the flexible extensions IhI3 N3 from the cover plate J1 oi the tank, the conductors M and K can be withdrawn upwardly to facilitate removal of the whole circuit-breaker :tor inspection or repair. The details of construction of the tubular casings and the withdrawable conductors do not in themselves torni part of the present invention.

The contact ring N1 is connected through a switch arm P in the chamber O to a terminal Q1 to which the cable or feeder Q is connected, the arm P being movable by suitable mechanism indicated at Pl from the opera-tive position (shown in full lines) into an earthing position (shown dotted) in which it makes contact with an earthed contact P2 on the wall of the chamber O.' A further switch arm R may also be provided, which can be moved from a normal inoperative position into a position (shown dotted) in which it earths the cable terminal Q1.

Suitable interlocking mechanism not shown) may be provided to prevent the two, isolating switches D, E, F from occupying their operative positionsat the sameY time, it as is sometimes the case it is desirable to prevent the two busbars A from being connected together. Interlocking mechanism may also be provided having the usual func tion of preventing operation of an isolating switch while the main circuit-breaker contacts L, L1, L2 closed. p

It will be appreciated that the improved switchgear considerably reduces the risk ot" both busbar circuits being placed out ot action at the same time and greatly facilitates the safe inspection and repair of either oi the busbars or isolating switches whilst service is maintained on the other bar.

What I claim as my invention and desire to secure by Letters vPatent is 1. In metal-clad electric switchgear for use in high voltage duplicate busbar systems, the combination of a circuit-breaker, two busbars to be selectively connected thereto, a separate chamber for each busbar, a third chamyber adjacent to the busbar chambers, two doub le-ended rotary isolating switches respectively passing from the two busbar chambers into the third chamber, and means whereby rotation of either isolating switch causes it to make or break the connection from its busbar to the circuit-breaker both in the busbar chamber and in the third chamber. 2. In metal clad electric switchgear for use in high voltage duplicate busbar systems, the combination of a circuit-breaker, two bus bars to be selectively connected thereto, a separate chamber for each busbar, a busbar contact in each such chamber, a third chamber adjacent to the busbar chambers, a contact in the third chamber connected to the circuit-breaker, two rotary isolating switches respectively passing from the two busbar chambers into the third chamber and each comprising an insulating bushing, a conductor within such bushing and a switch arm at each end of the conductor, and means whereby rotation of either isolating switch causes its two switch arms to engage with or be disengaged from the busbar contact and the contact connected to the circuit-breaker. 3. In metal-clad electric switchgear for use in high voltage duplicate busbar systems, the combination of a circuit-breaker, two busbars to be selectively connected thereto, a separate chamber for each busbar, a busbar contact in each such chamber, a third chamber adjacent to the busbar chambers, a -contact in the third chamber connected to the circuit-breaker, earthed contacts in the three chambers, two rotary isolating switches respectively passing from the two busbar chambers into the third chamber and each comprising an insulating bushing, a conductor within such bushing and a switch arm at each end of the conductor, and means whereby either isolating switch can be rotated to bring its switch arms into engagement either i withtlie earthed contacts or with thetbusbar contact and the contact connected to the circuit breaker. Y

4. In a metal-clad electric switchgear for use in high voltage duplicate busbar systems, the combination of a circuit-breaker, a tank containing the circuit-breaker, two busbars to be selectively connected to the circuitbreaker, a separate chamber for each busbar, a third chamber between the circuit-breaker tank and the busbar chambers, a conductor leading from the circuit-'breaker into the third chamber, two isolating switches respectively passing from the two busbar chambers into the third chamber, and meansfor operating each isolating switch whereby it will connect its busbar to the conductor leading from the circuit-breaker or will break such connection at two points one in the bus- A par chamber and the other in the third chamier.

5. In metal-clad electric switchgear for use 1n high voltage duplicate busbar systems, the combination of a circuit-breaker, an oilfilled tank containing the circuit-breaker,

two busbars to be selectively connected to the circuit-breaker, a separate oil-filled chamber for each busbar, a third oil-filled chamber disposed above the circuit-breaker tank and beneath the busbar chambers, a tubular casing passing through the third chamber, a conductor connected to the circuit-breaker and withdrawably mounted in the tubular casing, two rotary isolating switches respectively passing from the two busbar chambers into the third chamber and controlling the connections from the busbars to the withdrawable conductor, and means whereby rotation of either isolating switch causes it to break such connection both in the busbar chamber and in the third chamber.

6. In metal-clad electric switchgear for use in high voltage duplicate busbar systems, the combination of a circuit-breaker, an oil-filled tank containing the circuit-breaker, two busbars to be selectively connected to the circuit-breaker, a separate oil-filled chamber for each busbar, a third oil-filled chamber disposed above the circuit-breaker tank and beneath the busbar chambers, a busbar contact in each busbar chamber, a tubular casing passing through the third chamber, a contact on such casing within the third chamber, a conductor connecting such contact with the circuit-breaker and withdrawably mounted in the tubular casing, earthed contacts in the busbar chambers and in the third chamber, two rotary isolating switches respectively passing from the two busbar chambers into the third chamber and each comprising an insulating bushing, a conductor within such bushing and a switch arm at each end of the conductor, and means whereby either isolating switch can be rotated to bring its switch arms into engagement either with the earthed contacts or with the busbar contact and the contact on the tubular casing.

In testimony whereof I have signed my name to this speciication.

JOHN CHRISTIE. 

